Toothed locking arrangements have been used heretofore in connection with various devices for tightening objects. For example, plastic tightening devices used to fasten together cables and cable strands are commercially available which are provided at one band end with vertical teeth projecting outwardly, i.e., perpendicularly with respect to the plane of the band and, at the other end, with a lug having a detent element within the lug adapted to engage with the vertically disposed teeth.
Toothed locking arrangements are also known in connection with hose clamps. For example, the U.S. Pat. No. 2,374,541 discloses radially outwardly extending ratchet teeth with which a spring tongue is adapted to engage. Another clamp provided with outwardly extending teeth is disclosed in U.S. Pat. No. 3,925,851 in which a form-locking connection of the open ends of the clamping band is attained by the external and internal teeth of both band ends engaging in one another. However, as the form-locking connection of this clamp can be released only by lateral deflection of the clamping band, this type of clamp is made from plastic material because such material allows more readily lateral deflection.
In addition to vertically disposed toothed locking arrangements, i.e., with teeth extending outwardly of and more or less perpendicularly to the plane of the clamping band, toothed locking arrangements are also known which are essentially within the plane of the clamping band itself. The U.S. Pat. No. 2,405,912 discloses internal ratchet teeth provided on both sides of a slot that extends longitudinally in one band end while the other band end is provided with a T-shaped stud that is adapted to engage with the oppositely disposed ratchet teeth after passing through an enlarged opening.
Apart from complicated structures involving high manufacturing costs, the prior art patents all entail the disadvantage that they are unable to assure a clamp structure with internal clamping surfaces devoid of steps, offsets or discontinuities to assure a completely satisfactory, fluid-tight clamping action over the entire 360.degree. circumference of the object to be fastened.
My prior U.S. Pat. Nos. 4,299,012 and 4,315,348 disclose so-called "stepless" clamps, i.e., clamps without offsets, steps or discontinuities along the internal clamping surfaces and which are adapted to be tightened by plastic deformation of so-called "Oetiker" ears. These prior art clamps in which the gap underneath the "Oetiker" ear was bridged by the full band width, have proved extraordinarily successful and have been sold by the hundreds of millions. However, the clamp structures disclosed in my aforementioned two U.S. patents are not reusable, i.e., once the plastically deformed ear is deformed, the clamp can only be disassembled by destruction of the ear. So-called stepless earless clamps, which have also enjoyed immense commercial success, are disclosed in my prior U.S. Pat. Nos. 4,492,004 and 4,987,651. Though reusable, these types of clamps are designed normally for only one size of the object (hose) to be fastened and are still relatively complicated in structure.